<!doctype HTML>
<style>
.posabs { position: absolute; }
</style>
<span style="opacity: 0.5">
  <div id=target class=posabs></div>
</span>
<script>
if (window.testRunner) {
  window.testRunner.waitUntilDone();
  window.testRunner.dumpAsText();
}

requestAnimationFrame(() =>
  requestAnimationFrame(() => {
    target.className = '';
    if (window.testRunner)
        window.testRunner.notifyDone();
  }));
</script>
